Chelsea to lose Juan Mata and Fernando Torres for season opener

José Mourinho is resigned to being without his Spanish trio Juan Mata, Fernando Torres and César Azpilicueta when Chelsea start their Premier League campaign at home to Hull City on 18 August.

The trio are due back in London only 24 hours before the opener after Spain's friendly in Ecuador.

The World Cup and European Championship winners will play in Guayaquil on 14 August, the night England host Scotland at Wembley, with all three of Chelsea's Spanish contingent expected to be included in Vicente del Bosque's squad. Mourinho is already planning his team for the visit of promoted Hull on the following Sunday and, while the extra 24 hours granted by television coverage means the trio could be included on the bench, the Chelsea manager does not anticipate starting with any of the three.

"My lineup will depend a lot on which players go away with their national teams two days before the opening of the Premier League," Mourinho said. "If one has to go to Ecuador and comes back and arrives in London on Saturday without having slept after a 15-hour flight, coming in to train on Saturday morning, I don't think he is going to play on Sunday. If a player plays for England on Wednesday against Scotland, let's say plays for 45 minutes at Wembley and then an hour after the game he is at home in Cobham sleeping, he is in a better condition to play. The team will be decided game after game and week after week.

"What happens before the Hull City game has an impact. Also, if we have to play against Aston Villa two or three days later – we still don't know when that will be [the game is still to be rescheduled, having been set for the weekend Chelsea play in the European Super Cup in Prague on 30 August] – I will have to think about two or three matches at the same time. If the game is postponed until two months later and I have only one match in a week, I will think differently. It depends on the situation."

Chelsea arrive in Jakarta on Tuesday to prepare for their game against an Indonesia All Star XI on Thursday, with the manager still assessing his options and his players attempting to impress. While youngsters such as Kevin De Bruyne, who is fling back to London for a scan on the knee he injured in Malaysia, and Romelu Lukaku are expected to stay at the club, Mourinho has already decided to loan out Nathaniel Chalobah, Lucas Piazón and Josh McEachran for the season to gain further senior experience. Chelsea are assessing whether they can be placed at Premier League or Championship clubs.

Chalobah played in central midfield for Watford last term, Piazón had six months with Málaga, while McEachran spent the season under Tony Mowbray at Middlesbrough.

"We are thinking of letting Nathaniel go on loan for a last season," Mourinho said. "That is our intention and he knows. We have discussed that with him. He is a very, very good player. I like him very much and am very impressed. For sure, he is a Chelsea player. We will see whether or not it is a Premier League club but he would have to play every weekend for the last year of his loan period. He could be in our squad already but we think one more season will help and then he will come back for 2014-15. It will be his last one out on loan. He is very, very good.

"Josh will also go on loan, Lucas Piazón too. Wallace will go on loan – he has no work permit and will go on loan in Europe, not in South America, to make the transfer easier for him. Islam Feruz will stay in our under-21s."

Mourinho has already confirmed that Bertrand Traoré, the promising 17-year-old Burkina Faso international, will sign professional terms on his 18th birthday and, should he fail to secure a work permit, will be loaned to a European club in the hope that he will earn the necessary clearance.

Another promising youngster, the Czech centre-half Tomas Kalas, will be a part of the senior setup for the campaign ahead. The defender, 20, a £5.2m signing from Sigma Olomouc in 2010, has spent the past two years on loan at Vitesse Arnhem but will offer Mourinho valuable cover across his back line.

"It was the first day of training when Mr Mourinho came to me and asked me if I would accept the challenge to be a first-team player and give it everything and, of course, I accepted," said Kalas, who played last season largely at right-back. "I hope I am ready but now I have to prove myself.

"I have no doubts. I played 63 games in Holland and another season maybe would be worse than better. I learned a lot of technical and tactical skills playing in the Eredivisie, where everybody plays football from the goalkeeper to the central defender. To play 10 or 20 games for Chelsea would be brilliant."